Astrolabe
The astrolabe was one of the artefacts found in the Brass Bound Chest. It was claimed by Jarre. Origin of the Artefact An astrolabe (Greek: ἁστρολάβονastrolabon 'star-taker')1 is a historical astronomical instrument used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars; determining local time (given local latitude) and vice-versa; surveying; triangulation; and to cast horoscopes. They were used in Classical Antiquity and through the Islamic Golden Age and the European Middle Ages and Renaissance for all these purposes. In the Islamic world, they were also used to calculate the Qibla and to find the times for Salah prayers. The first known metal astrolabe known in Western Europe was developed in the 15th century by Rabbi Abraham Zacuto in Lisbon. Metal astrolabes improved on the accuracy of their wooden precursors. In the 15th century, the French instrument-maker Jean Fusoris (ca. 1365–1436) also started selling astrolabes in his shop in Paris, along with portable sundials and other popular scientific gadgets of the day. In the 16th century, Johannes Stöffler published Elucidatio fabricae ususque astrolabii, a manual of the construction and use of the astrolabe. Four identical 16th century astrolabes made by Georg Hartmann provide some of the earliest evidence for batch production by division of labor. An astrolabe consists of a disk, called the mater (mother), which is deep enough to hold one or more flat plates called tympans, or climates. A tympan is made for a specific latitude and is engraved with astereographic projection of circles denoting azimuth and altitude and representing the portion of the celestial sphere above the local horizon. The rim of the mater is typically graduated into hours of time, degrees ofarc, or both. Above the mater and tympan, the rete, a framework bearing a projection of the ecliptic plane and several pointers indicating the positions of the brightest stars, is free to rotate. Some astrolabes have a narrow rule or label which rotates over the rete, and may be marked with a scale of declinations. The rete, representing the sky, functions as a star chart. When it is rotated, the stars and the ecliptic move over the projection of the coordinates on the tympan. One complete rotation corresponds to the passage of a day. The astrolabe is therefore a predecessor of the modern planisphere. On the back of the mater there is often engraved a number of scales that are useful in the astrolabe's various applications; these vary from designer to designer, but might include curves for time conversions, acalendar for converting the day of the month to the sun's position on the ecliptic, trigonometric scales, and a graduation of 360 degrees around the back edge. The alidade is attached to the back face. An alidade can be seen in the lower right illustration of the Persian astrolabe above. When the astrolabe is held vertically, the alidade can be rotated and the sun or a star sighted along its length, so that its altitude in degrees can be read ("taken") from the graduated edge of the astrolabe. Effect of the Artefact The effect of this item is not yet known. Category:Contents of the Chest